1. Field of the Invention
The present invention relates to a press machine monitoring facility, and, more particularly, to a method and system for dynamically monitoring the peak compressive and tensile acceleration activity occurring within a press machine to determine an operating condition based upon a comparison of the peak load values to machine-specific capacity levels.
2. Description of the Related Art
Monitoring the load levels within a press machine plays a vital role in properly evaluating the performance of the processing activity to ensure that machine components such as the slide assembly are being operated within acceptable tolerances. The rapid identification of an out-of-bounds operating condition allows corrective action to be immediately undertaken, such as terminating machine operation or adequately adjusting the slide movement. Otherwise, the continued operation of a press machine at above-threshold levels, coupled with the inability to accurately detect the occurrence of load levels that exceed the capacity ratings, may lead to a progressive degradation in the integrity of the workpiece and eventual breakdown of the machine components. Mechanical failures could include the complete shearing or fracturing of individual coupling links in the connection assembly or physical damage to fastening elements such as slide adjustment nuts and connection screws. Complete destruction of the press machine may result if the magnitude of the operating load level exceeds the capacity threshold by a sufficient amount or if the out-of-bounds condition is sustained for a sufficient period of time. Efforts to address this problem have led to the development of various types of monitoring apparatus designed to provide process supervision aimed at detecting when the compression-type forces exhibit load values that exceed predetermined threshold capacity levels.
One conventional approach employs measurement apparatus such as stress/strain gauges configured within the uprights of the press frame structure to measure the vibrational activity present within the machine. Apparatus of this type essentially operate by registering the magnitude of the vibrational energy content occurring over a given period of time such as a press production cycle. These sensors provide a measurement of the dimensional deformation or other such physical disturbances occurring in the press machine. Any changes measured by the strain gauge sensor with respect to the dimensional characteristics of the relevant machine part represent the force or load level that is being developed within the machine at the measurement location.
These sensing devices, however, utilize a form of time-averaging which makes them unsuitable for analyzing low-speed applications and detecting peak load level conditions. The measurement data generated by strain gauge sensors represents the change in vibrational energy content that takes place over a certain measuring interval. Thus, even if a peak load level occurs and is registered by the strain gauge sensor, this event may not be recognizable in the output vibrational energy data due to its summation with other comparatively lower vibrational energy measurements. What then happens, particularly during low-speed applications, is that the measured vibrational energy which corresponds to a peak load level becomes obscured or xe2x80x9csmoothed-outxe2x80x9d when combined or averaged with the predominantly low levels of vibrational energy content that appear during the rest of the press machine monitoring period. Consequently, although peak load values may occur that exceed the press machine capacity levels, the occurrence of such adverse operating conditions will remain undetected during those monitoring periods where the overall vibrational energy content is sufficiently low such that the generated measurement data indicates an average energy content well below the out-of-bounds level. This presents a particular problem in adequately evaluating low-speed applications that oftentimes include rapid changes in acceleration which typically occur over relatively short time durations, thereby producing a change in the vibrational energy content, that can easily be masked by comparatively lower levels of measured vibrational energy present during other time frames of the monitoring interval.
These conventional sensor devices also do not take into account the different evaluation requirements attending a tensile process and a compression process. Press machines are typically configured so that certain load-bearing components have a higher capacity rating in one direction than the other. For example, saddle bushings and ball bushings are typically designed to provide a level of load-bearing support in the compression direction that is comparatively higher than that provided in the tensile direction. With machines of this type that are designed primarily for compressive applications, the use of the press machine for a tensile application or for an application that requires sufficient tensile acceleration has the potential of creating an operating condition that will lead to parts failure and/or workpiece malformation. Sensor apparatus that rely upon measuring the change in vibrational energy content do not have a mechanism for distinguishing between whether the measurement data is attributable to a compressive-type application or a tensile-type application. The ability to differentiate between these two types of forces has particular importance in those press machines where the compressive and tensile capacity levels vary significantly, requiring a means to incorporate this difference into the evaluation strategy. For example, in a machine having a 200 ton compression capacity rating and a tensile rating representing 10% of the compression capacity, the maximum tensile load level is 20 tons. Current approaches do not provide a facility to distinguish between compression and tensile load level measurements, nor do they incorporate load level capacity data which accurately reflects the different capacity ratings depending upon the force direction, i.e., tensile or compression.
In view of the foregoing, there is a demonstrated need for a facility capable of dynamically identifying the occurrence of adverse operating conditions arising from a compressive and/or tensile force that currently exceeds or may eventually exceed the rated capacity of the press machine.
According to the present invention there is provided a method and system for evaluating the operating condition of a press machine based upon a comparison between load level capacity data and measurement data representing peak acceleration values of the slide assembly. A measuring device in the form of an accelerometer or other such transducer dynamically generates acceleration signals representing real-time measurements of the acceleration of the slide assembly. These acceleration signals are processed to identify which ones correspond to a peak acceleration condition for the slide assembly. The peak acceleration signals represent peak operating load levels being developed within the press machine. A data means in the form of a storage facility provides load level capacity data which represents the maximum allowable compressive and tensile load levels for the press machine under study. The capacity data is preferably provided in the form of a plurality of press machine operating zones each representing a corresponding range of load values and each having a respective rating factor associated therewith. The rating factor indicates the relationship of the particular press machine operating zone to a respective one of the maximum allowable compressive and tensile load levels. A processor evaluates the peak load levels in relation to the operating zone data to determine which respective ones of the plurality of press machine operating zones encompass each respective one of the peak load levels. The operating condition of the press machine is determined in accordance with the peak operating load levels (as represented by the corresponding measured peak acceleration values) and the respective rating factors associated with the respective press machine operating zones which are determined by the processor to encompass the peak load levels.
The invention, in one form thereof, comprises an assembly for use in monitoring the operation of a press machine, preferably in a dynamic manner throughout at least one press operating cycle. The monitoring assembly includes a data means for providing load level capacity data associated with the press machine. The load level capacity data preferably includes a representation of a maximum allowable compressive load level and/or a representation of a maximum allowable tensile load level. More particularly, the data means preferably includes a means for providing operating zone data defining a plurality of press machine operating zones each representing a corresponding range of load values. The monitoring assembly further includes a measurement means such as an accelerometer for providing a measure of the acceleration activity present within the press machine, wherein the acceleration activity measurement is representative of a load level measurement. An evaluation means compares the load level measurement with the load level capacity data and then provides an indication of an operating condition of the press machine based upon this comparison.
This indication of the operating condition of the press machine is preferably displayed in a visible or audible form via an annunciator panel which forms part of a display means. For example, an annunciator means may be provided, which is responsive to the occurrence of an out-of-bounds operating load level condition as indicated by the load level comparison result generated by the evaluation means, for providing an indication of the occurrence of the out-of-bounds operating load level condition.
The evaluation means, in one form thereof, further includes a processing means for evaluating the load level measurement in relation to the operating zone data to determine which ones of the plurality of press machine operating zones encompass the load level measurement. Each respective one of the press machine operating zones is provided with a respective rating factor which indicates the relationship of the respective one press machine operating zone to at least one of a threshold compressive load level and a threshold tensile load level. A means is provided for determining the operating condition of the press machine in accordance with the acceleration activity measurement provided by the measurement means and the respective rating factors associated with the respective press machine operating zones determined by the processing means to encompass the load level measurement represented by the acceleration activity measurement.
The measurement means, in one form thereof, includes a peak detector means for generating at least one peak acceleration signal each representing a respective peak load level developed within the press machine. Accordingly, the evaluation means, in another form thereof, further includes a processing means for evaluating the at least one peak load level generated by the peak detector means in relation to the operating zone data to determine which respective one of the plurality of press machine operating zones encompasses each respective one of the at least one peak load level. A means is provided to determine the operating condition of the press machine in accordance with at least the of the at least one peak acceleration signal and the respective press machine operating zone determined by the processing means to encompass the respective peak load level represented by the at least one of the at least one peak acceleration signal.
The evaluation means, in yet another form thereof, further comprises an analysis means, which is responsive to a plurality of acceleration values provided by the measurement means during a corresponding press cycle interval, for identifying ones of the plurality of acceleration values which satisfy a selectable signal characteristic criteria to thereby define a selected acceleration signal group. The analysis means compares the respective operating load level represented by each respective one of the selected acceleration signal group with the load level capacity data, and then provides an indication of an operating condition of the press machine in accordance with this comparison. This selectable signal characteristic criteria preferably represents a peak acceleration condition.
The monitoring assembly, in another form thereof, may optionally include a control means which is arranged to selectively activate the measurement means and the evaluation means only when the press machine designated for monitoring satisfies an authorization condition. This authorization condition is satisfied when the press machine designated for monitoring corresponds to at least one of an authorized press machine, an authorized family of press machines, and a press machine from an authorized manufacturer.
The monitoring assembly, in yet another form thereof, may optionally include a selection means responsive to a control signal for selectively activating the evaluation means in accordance with the control signal to thereby enable operation of the evaluation means during a selective one of press machine compression activity and press machine tensile activity. For this purpose, there is provided a means, responsive to the acceleration activity measurement provided by the measurement means, for determining whether the acceleration measurement corresponds to a one of compression activity and tensile activity and for generating a signal based upon this determination to control the selection means.
The monitoring assembly, in yet another form thereof, may optionally include a recordation means for recording the respective operating load level corresponding to each respective one of the plurality of acceleration measurements generated by the measurement means. A retrieval means controllably accesses and retrieves from the recordation means selectable ones of the recorded operating load levels corresponding to a selective one of press machine compression activity and press machine tensile activity. The selected ones of the recorded operating load levels are applied to the evaluation means for comparison with the load level capacity data to thereby generate a selected load level comparison result. This selected load level comparison result serves as the basis for providing an indication of the operating condition of the press machine.
The monitoring assembly, in still yet another form thereof, may optionally include a timer means for selectively activating at least one of the measurement means and the evaluation means to enable respective operation thereof over a selectable time period.
The invention, in yet another form thereof, comprises a system for use with a press machine. The monitoring system includes a data means for providing load level capacity data associated with the press machine. A sensor assembly dynamically measures the acceleration activity occurring within the press machine to thereby generate a plurality of acceleration signals representing a corresponding plurality of load level values. There is further provided a processor means, which is responsive to the plurality of acceleration signals generated by the sensor assembly, for determining an operating state of the press machine based at least in part upon a comparison between the load level capacity data and at least one of the plurality of load level values.
The processor means, in one form thereof, determines the operating state of the press machine by: (i) identifying ones of the plurality of acceleration signals each representing a respective peak acceleration condition to thereby define a peak acceleration signal group; (ii) comparing the corresponding load level value for each respective one of the peak acceleration signal group with the load level capacity data to thereby generate a peak level comparison result; and (iii) providing an indication of the operating state of the press machine in accordance with the peak level comparison result.
The data means, in one form thereof, further includes a means for defining a plurality of press machine operating zones each representing a corresponding range of load values. The processor means provides the indication of the operating state of the press machine in accordance with a determination of which respective one of the plurality of press machine operating zones encompasses each respective one of the peak acceleration signal group. The load level capacity data preferably includes a representation of a maximum allowable compressive load level and/or a representation of a maximum allowable tensile load level.
The invention, in yet another form thereof, comprises a system for use in monitoring the operation of a press machine. The monitoring system includes a data means for providing load level capacity data associated with the press machine. A measurement means provides a measure of the peak load levels developed within the press machine. An evaluation means determines an operating state of the press machine based at least in part upon a comparison between the peak load levels measurement provided by the measurement means and the load level capacity data.
The data means, in one form thereof, includes a means for defining a plurality of press machine operating zones each representing a corresponding range of load values. These operating zones are preferably defined in relation to at least one of a maximum allowable compressive load level and a maximum allowable tensile load level. The evaluation means determines the operating state of the press machine in accordance with a determination of which respective one of the plurality of press machine operating zones encompasses each respective one of the measured peak load levels provided by the measurement means.
The measurement means, in one form thereof, further includes a signal means provided in the form of an accelerometer for generating at least one peak acceleration signal each representing a respective peak load level developed within the press machine. These peak acceleration signals are then processed by the evaluation means to determine the particular operating zones that are associated with the peak load levels represented by the peak acceleration signals. The evaluation means generates an indication of the operating condition of the press machine based upon the peak load levels and the appropriate operating zones associated therewith.
The invention, in yet another form thereof, comprises a method of monitoring the operation of a press machine. The method includes the steps of providing a measure of the load level being developed within the press machine; providing capacity data indicating load level capacity values for the press machine; and evaluating the operation of the press machine by comparing the load level measurement with the capacity data.
The step of providing the load level measurement further comprises the step of generating a plurality of acceleration signals representative of the acceleration activity occurring within the press machine. The step of providing capacity data further comprises the step of defining a plurality of press machine operating zones each representing a corresponding range of load values. The plurality of press machine operating zones are preferably defined in relation to at least one of a maximum allowable compressive load level and a maximum allowable tensile load level.
The evaluation step further comprises the steps of (i) identifying which ones of the generated plurality of acceleration signals represent the occurrence of a respective peak acceleration condition to thereby define a peak acceleration signal group; (ii) determining which respective one of the plurality of press machine operating zones encompasses each respective one of the peak acceleration signal group; and (iii) determining an operating state for the press machine in accordance with the respective press machine operating zone determined to encompass each respective one of the peak acceleration signal group.
The invention, in yet another form thereof, comprises a method of monitoring the operation of a press machine. The method comprises the steps of providing a measure of the peak load levels developed within the press machine; providing capacity data indicating load level capacity values for the press machine; and evaluating the operation of the press machine by comparing the peak load levels measurement with the capacity data.
The step of providing a measure of the peak load levels further comprises the step of generating at least one peak acceleration signal each representing a respective peak load level within the press machine. The step of providing capacity data further comprises the step of defining a plurality of press machine operating zones each representing a corresponding range of load values. The plurality of press machine operating zones are preferably defined in relation to at least one of a maximum allowable compressive load level and a maximum allowable tensile load level.
The evaluation step further comprises the steps of (i) determining which respective one of the plurality of press machine operating zones encompasses each respective one of the at least one peak acceleration signal; and (ii) determining an operating state for the press machine in accordance with the respective press machine operating zone determined to encompass each respective one of the at least one peak acceleration signal.
One advantage of the present invention is that the monitoring system provides continuous, real-time readings of the compressive/tensile load conditions present during press machine operation to thereby enable dynamic monitoring of the severity level of the press operation.
Another advantage of the present invention is that the monitoring system enables accurate identification of the peak compressive/tensile load levels being developed within the press machine, which allows a comparison with the maximum permissible compressive/tensile load levels to determine whether the press machine is operating within acceptable margins.
A further advantage of the invention is that the evaluation strategy which is adopted for determining the operating condition of the press machine makes use of a rating system that weights each peak load level measurement based upon its comparative relationship to operating zone data which is represented by a plurality of press machine operating zones each defining a corresponding range of load values.
A further advantage of the invention is that the results of the comparative analysis between the load level capacity data and the peak acceleration measurement data is expressed in the form of a readily understandable performance indicator which represents the application severity level of the press machine operation, thereby providing the user with a means to quickly assess the operating state of the machine.
A further advantage of the invention is that the monitoring system is particularly well-suited to analyzing the load conditions developed during slow-speed applications due to the accuracy and reliability in determining the operating load levels, which is attributable to the use of acceleration measurements as the basis for evaluating the load levels.
A further advantage of the invention is that the monitoring system provides a means to evaluate the operating condition of the press machine which recognizes the type of acceleration activity taking place in the press machine (i.e., compressive or tensile) and which takes into account the different capacity levels for compression and tensile loading.
A further advantage of the invention is that the monitoring system is easily configurable as an integrated portable instrument or as a console mounted unit having various display features.
A further advantage of the invention is that the monitoring system is adaptable for use on a variety of press machines over a wide range of production processes.
A further advantage of the invention is that the monitoring system provides various optional features to enhance its utility and interfacing capabilities, such as a communications module to transmit data and other event-indicators over an internet connection, voice or sound announcers, lights, capacity-exceeding alarms, pager alerts, and text processing and signaling.
A yet further advantage of the invention is that the monitoring system includes a lock or latch mechanism to prohibit use of the apparatus on an unauthorized press, thereby promoting quality control and ensuring accurate evaluation results.